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prenatal screening info, genetic testing

July 31 2012 at 3:40 PM
jkl  (no login)

I wanted to repost this here as it's a common question that comes up and I wanted to put it under better searchable terms. I'm also wondering if JM should put it up top. I know she went on vacation so maybe I will bring it up again when she is back. Please feel free to chime in if any of the info is not right, times etc. Once it's edited maybe it can go up top. I think it would be useful as sometimes you don't have much time by the time you get into see an OB to do these tests, and also I don't find the brochures that they give out all that useful or comprehensive.

Prenatal testing:

noninvasive:

1st trimester screen: 11-13 weeks, u/s (measuring nuchal translucency and looking for the presence of the nasal bone) and bloodwork that give you odds for the most common chromosomal abnormalities (including down's)

a new test, called MaterniT21, tests your bloodwork for small amounts of the baby's DNA and can tell you about whether the baby has the 3 most common chromosomal disorders (including down's). i think can be done as early as 9-10wks and has an accuracy of around 99%, but others may know more about this as they are using it it right now (insurance may not cover as it is a new test)

2nd trimester screen: also called AFP--18-21 weeks(?) bloodwork gives you another odds ratio for the chromosomal disorders, also can give you info about spina bifida and soem other things but my OB says these things would be seen on the level II u/s. My understanding is that this test is less reliable than the 1st tri screen (and thus I am not doing it) but others may have different info

level II u/s: 18-20 weeks, give good info about general health and development of the baby, and detects soft markers for down's.


Invasive (chance for inducing m/c-- can vary from practice to practice)

cvs: 11-13 weeks (?), detects chromosomal abnormalities

amniocentesis: 14-15 weeks onward, detects chromosomal abnormalities and spina bifida



 
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Teresa
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Alpha Feto Protein**

July 31 2012, 5:19 PM 

this blood work can be done from 15-20 weeks. I am 16 weeks and having mine done this Thursday, just wanted to note that.

This is a great idea, very helpful! Good call out!

 
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jkl
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thanks!

August 1 2012, 3:44 PM 


Yes, I wasn't sure about the earliest time, I am 18 weeks so my OB was asking me about it and I know it goes until 21 weeks because I was trying to figure out how much time I had to decide. I think I am not doing it, just because I have heard it has higher false positives and negatives compared to the 1st tri screen. I have my level II on friday so hopefully there will be no red flags from that. Good luck with yours!

jkl

 
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Teresa
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Totally with you on that one...

August 2 2012, 12:56 PM 

Just came from the Dr and had the conversation with her and you are right, they do come back high, especially if you tested high the first round. I told her under no circumstances do I want to hear any numbers anymore. The baby is coming as it is, I am not going to put myself through that torture agaian of hearing I am high risk. Its not like I am going to change my mind and do an amnio either. Good luck with your results!!

 
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BroodyHen
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Re: prenatal screening info, genetic testing

August 1 2012, 11:26 AM 

thanks for doing this, jkl.
i wanted to add that there are two other companies that do the same testing as materniT21. verinata has the verify test and aria diagnostics has the harmony pernatal test. it sounds like they all use the same technology, but i'm not really sure.

 
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jkl
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thanks!

August 1 2012, 3:46 PM 


I will add those in. They all use the same approach but I don't know if they all use the same technology to extract the DNA etc. Hope you get some answers soon!

jkl

 
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